With the rapid development of the broadband technology and the rapid increase of broadband users, a crisis of Internet Protocol Version 4 (IPv4) address space is long-standing, and this is the major impetus causing the upgrade of Internet Protocol (IP) version. The China's Next Generation Internet (CNGI) demonstration project is a national strategic project, and the main object of the project is to construct a test platform for the next generation of Internet centered on the Internet Protocol Version 6 (IPv6). The start of the project indicates that the IPv6 of our country has entered a substantial development stage. All levels of operators are also aggressively deploying the V6 network, and the V6 broadband access network has gradually stepped into the stage of pre-commercial trials.
A design concept of the IPv6 base protocol is wishing that the V6 network can become a plug-and-play access network, but with regard to parts of operators, it is required to manage addresses in a stateful (i.e. dynamic address allocation) form, thus a Dynamic Host Configuration Protocol for IPv6 (DHCPv6) emerges, which causes that a Stateless Address Auto Configuration (SLAAC) function in a Neighbor Discovery Protocol (NDP) and a DHCPv6 protocol address allocation function coexist in the topology environment of existing IPv6 remote broadband access network.
Nowadays, typical IPv6 access user types provided by popular Broadband Remote Access Server (BRAS) router equipment include: an IPHOST (static dedicated line) user, a DCHPv6 user and an SLAAC user. With regard to different link ways, the DCHPv6 user and the SLAAC user can be divided into an Ethernet link user and a Point-to-Point Protocol Over Ethernet (PPPoE) link user.
Especially in the IPv6 networking, a multi-homed host becomes an increasingly important application scenario. Except for one wired network connection (e.g. the Ethernet), a host may also have one or more wireless connections, such as Bluetooth and 802.11 protocol and so on. Except for being connected with a physical link, a host may also be connected with a virtual network or a tunnel network. For example, except for being directly connected with a public Internet, a host may also be connected with a tunnel private and common network. With regard to an IPv6 transition scenario, one tunnel link may be probably added, for example, hosts may be connected with a 6 to 4 tunnel (RFC3056) network or a configuration tunnel (RFC2893) network.
However, in actual application of the BRAS router equipment, the SLAAC function of the NDP and the DHCPv6 protocol address allocation function are often used to allocate a prefix to the user, thereby triggering the user to generate an IPv6 address according to the prefix. Duplicate Address Detection (DAD) will be performed on an address generated by a new user within a scope of a local link, that is, the multicast of a DAD message is performed within the scope of the local link (FIG. 1 shows an encapsulation format of the DAD message), and it is to wait whether there is a reply. When the address has been online in the local link, a user using the address will reply a Neighbor Advertise (NA) message to a new user who generates the address later (FIG. 2 shows an encapsulation format of the NA message), and informs the new user that the address cannot be used, for the address has been used by the node within the scope of the local link. At this point, the new user sending the DAD message and receiving the NA message replied by the neighbor node needs to mark a duplicate tag on the address generated by the user itself, and waits for manual reconfiguration. If the new user performs the DAD detection for specified times (Note: the default times of DAD detection are different according to the difference of equipment, it must be greater than one time, generally it is to detect three times, and each interval time is one second), an NA message replied by other nodes within the scope of the local link is not received yet, it is proved that there is no conflict for the address within the scope of the local link, that is, the new user can normally use the address. In the process of the new user generating the address according to the prefix allocated by the BRAS router equipment, the new user supports generating more addresses at one time or generating one or more addresses at multiple times according to one prefix, and also supports manually configuring one or more addresses.
The environment as described above belongs to a universal phenomenon when the IPv6 user of the BRAS router equipment performs accessing, especially in an application scenario of prefix sharing. The scenario of prefix sharing can be described as an application scenario that the BRAS router equipment allocates the same prefix to multiple users. Such content of protocol brings tremendous test and difficulty to the user management of the BRAS router equipment. When the user generates one or more addresses, after a user generating an address later receives an NA message with respect to the address, even though the user who is using the address releases the address, the user generating the address later also will not perform DAD detection on the address again and start the address, which causes a waste of address resources; moreover, after the user releases the address, the BRAS router equipment will still perform charging on the user, which causes charging the user incorrectly, and increases unreasonable expenses of the user.